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Systematic (IUPAC) name
CAS number 145-13-1
ATC code ?
PubChem 8955
DrugBank EXPT02608
Chemical data
Formula C21H32O2 
Mol. mass 316.483 g/mol
Pharmacokinetic data
Bioavailability ?
Metabolism ?
Half life ?
Excretion ?
Therapeutic considerations
Pregnancy cat.


Legal status
Routes ?

Pregnenolone is a steroid hormone involved in the steroidogenesis of progesterone, mineralocorticoids, glucocorticoids, androgens, and estrogens. As such it is a prohormone.


Like other steroids, pregnenolone consists of four interconnected cyclic hydrocarbons. It contains ketone and hydroxyl functional groups, two methyl branches, and a double bond at C5, in the B cyclic hydrocarbon ring. Like all steroid hormones, it is hydrophobic. Its esterified version, pregnenolone sulfate, is water soluble.


Production of Pregnenolone from Cholesteol and further metabolism
Reaction: Pregnenolone-Progesterone

Pregnenolone is synthesized from cholesterol. This conversion involves hydroxylation at the side chain at C20 and C22 positions, with cleavage of the side chain. The enzyme performing this task is cytochrome P450scc, located in the mitochondria, and controlled by pituitary tropic hormones, such as ACTH, FSH, LH.


Pregnenolone undergoes further steroid metabolism in one of three ways.

  • Pregnenolone can be converted to androsta-5,16-dien-3 beta-ol by 16 ene synthetase.


Pregnenolone and its sulfate, like dehydroepiandrosterone and its sulfate and progesterone, belong to the group of neurosteroids that are found in high concentrations in certain areas in the brain and are synthesized there. Neurosteroids affect synaptic functioning, are neuroprotective, and enhance myelinization. Pregnenolone and its sulfate ester are under investigation for their potential to improve cognitive and memory functioning.[1]

Additional images


  1. Vallée M, Mayo W, Le Moal M (2001). "Role of pregnenolone, dehydroepiandrosterone and their sulfate esters on learning and memory in cognitive aging.". Brain Res Brain Res Rev. 37 (1-3): 301–12. PMID 11744095.